Long noncoding RNAs in breast cancer: Implications for pathogenesis, diagnosis, and therapy

Abstract

Human genome mapping has revealed that protein-coding genes represent less than 2 % of the total genome sequence, and simultaneously more than 75 % of the genome is actively transcribed into RNA. Recent studies of the human transcriptome led to the discovery of new heterogeneous group of transcripts-noncoding RNAs. The major part of these ncRNAs consists of long noncoding RNAs (lncRNAs), which differ in size, location on genome, and biological functions. Generally, through distinct mechanisms, they affect a number of biological processes, such as modulation of protein activity, alternative splicing of mRNA, and epigenetic regulation or microRNA silencing, and play a key role in transcriptional and posttranscriptional gene expression regulation. Deregulated levels of lncRNAs were observed with a wide range of tumors, including breast cancer. Gene expression patterns of lncRNAs are able to distinguish normal and tumor tissue or even various breast cancer stages, which makes them a potential diagnostic and prognostic biomarkers or therapeutic targets.